1. Field of the Invention
The present invention generally relates to radar systems and more particularly to a digital beamforming radar system that utilizes a modified commercially available low-noise block converter (LNB) in a receive signal path.
2. Description of the Prior Art
In conventional digital beamforming radar systems, an amplifier, mixer, filter, and analog-to-digital converter are connected to elements of an antenna array. Signals from respective analog-to-digital converters are then subjected to various beamforming algorithms in a digital processor.
In general, digital beamforming radars utilize high-frequency electromagnetic waves, such as microwaves or millimeter waves. Analog devices, such as amplifiers, filters, and mixers, which are able to operate at these frequencies, are typically very expensive.
In addition, conventional beamforming radars require a considerable quantity of these analog devices due to the corresponding number of elements in the antenna array. Accordingly, high production costs have become unavoidable.
One way to improve the performance of these radars is to increase the quantity of antenna elements. However, increasing the number of elements requires a correspondingly greater number of high-frequency analog devices, which also increases the cost of the system. In addition, increasing the number of analog devices results in increasing overall size requirements for the radar system.
A phased array receiving antenna, such as that used in a digital beamforming radar, includes an array of individual antenna elements and electronic phase shifting components, which are typically arranged in a planar array to receive an electromagnetic signal. Adjusting the phase shift and/or delay of a received signal through each of the elements and delay components and summing the signals enables the antenna to be electronically steered. Accurate electronic steering of the antenna requires that the relative phase shift and/or delay through each of the antenna elements and delay components be accurately known and adjusted.
Thus, the large number of discrete components required for beamforming radars creates various problems, such as those discussed above, as well as matching between components, periodic calibration, and variability of system performance. These problems become more critical when additional components are required due to an increase in antenna elements or to improve the performance and accuracy of the radar system.